package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }


    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    // 消息队列实现下单
    private class VoucherOrderHandler implements Runnable {
        String queueName = "streams.order";
        @Override
        public void run() {
            while (true) {
                try {
                    // 1.获取消息队列中的订单信息 xreadgroup group g1 c1 count 1 block 2000 streams streams.order >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    // 2.判断消息获取是否成功
                    if(list == null || list.isEmpty()){
                        // 2.1 如果获取失败，说明没有消息，继续下一次循环
                        continue;
                    }
                   // 3.解析消息中的订单消息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    // 4.如果获取成功，可以下单
                    handleVoucherOrder(voucherOrder);
                    // 5.ACK确认 sack streams.order g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    handlePendingList();
                }
            }
        }

        private void handlePendingList() {
            while (true) {
                try {
                    // 1.获取pending-list中的订单信息 xreadgroup group g1 c1 count 1  streams streams.order 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    // 2.判断消息获取是否成功
                    if(list == null || list.isEmpty()){
                        // 2.1 如果获取失败，说明pending-list没有消息，结束循环
                        break;
                    }
                    // 3.解析消息中的订单消息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    // 4.如果获取成功，可以下单
                    handleVoucherOrder(voucherOrder);
                    // 5.ACK确认 sack streams.order g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());
                } catch (Exception e) {
                    log.error("处理pending-list异常", e);
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }
    }

    /*// 阻塞队列实现下单
    private class VoucherOrderHandler implements Runnable {
        @Override
        public void run() {
            while (true) {
                try {
                    // 1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    // 2.创建订单
                    handleVoucherOrder(voucherOrder);

                } catch (InterruptedException e) {
                    log.error("处理订单异常", e);
                }
            }
        }
    }*/
    // 根据订单信息创建订单
    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        // 1.获取用户
        Long userId = voucherOrder.getUserId();
        // 2.创建锁对象
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        // 3.获取锁
        boolean isLock = lock.tryLock();
        // 4.判断是否获取锁成功
        if(!isLock){
            // 获取锁失败
            log.error("不允许重复下单");
            return;
        }
        try {
            // 创建订单
            proxy.createVoucherOrder(voucherOrder);
        } finally {
            // 释放锁
            lock.unlock();
        }
    }


    private IVoucherOrderService proxy;
    // 秒杀下单
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 获取用户
        Long userId = UserHolder.getUser().getId();
        // 获取订单id
        long orderId = redisIdWorker.nextId("order");
        // 1.执行lua脚本
        Long result = stringRedisTemplate.execute(SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString(),
                String.valueOf(orderId)
        );
        // 2.判断结果是否为0
        int r = result.intValue();
        if(r != 0){
            // 2.1 不为0，没有购买资格
            return Result.fail(r == 1?"库存不足":"不能重复下单");
        }
        // 3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 4.返回订单id
        return Result.ok(orderId);
    }


    // 创建订单
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        // 4.一人一单
        Long userId = voucherOrder.getUserId();
        // 4.1 查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        // 4.2 判断是否存在
        if (count > 0){
            // 用户已经买过了
            log.error("用户已经购买过一次了！");
            return;
        }
        // 5.扣减库存
        boolean success = seckillVoucherService.update().
                setSql("stock = stock - 1")  //set stock=stock-1
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock",0)// where id= ? and stock > 0
                .update();
        if (!success){
            // 扣减失败
            log.error("库存不足！");
            return;
        }
       // 保存订单
        save(voucherOrder);
    }
}
